Your budget is a challenge, but I would recommend going another direction - an old japanese tractor (subcompact before the term applied) instead of a gas garden tractor.
Model numbers to look for: Kubota
B5100,
B6100,
B4200,
B6000
Satoh/Mitsubishi Beaver, MT372, MT160
Yanmar 1300, 1500 (grey market)
Ford 1100, 1200
I have owned a
B6000 and now have a Satoh Beaver with FEL, these are bullet-proof diesel tractors with very heavy frames, axles, PTO and built in hydraulics. Although I sometimes see these tractors (2wd) in the $1,500 range, they are a bit tough to find at those prices - clean tractors with an attachment often run closer to $3,000...
Anyhow, I have an old allis chalmers garden tractor, tough as nails, but it isnt half as useful as my Beaver....and the loader and tiller on the Beaver makes it the ultimate gardening machine. Good luck on whatever you find!